See the bold text below:

Section 958 CMR 3.500. Disenrollment of Primary Care Provider

Continuity of Care Post-Contract

Where a carrier allows or requires the designation of a primary care provider, the carrier shall in the event of disenrollment of a primary care provider for reasons other than those related to quality or fraud:

(1) provide to any insured written notice of the disenrollment of the insured’s primary care provider at least 30 days prior to any such disenrollment;

(2) include in said notice a description of the procedure for choosing an alternate primary care provider; and

(3) permit the insured to be covered for health services, consistent with the terms of the carrier’s evidence of coverage, provided by such primary care provider for at least 30 days after the provider is disenrolled.

Section 958 CMR 3.501. Disenrollment of Providers of Care to Pregnant Women

Continuity of Care Post-Contract

Carriers shall allow any female insured who is in her second or third trimester of pregnancy and whose provider in connection with said pregnancy is involuntarily disenrolled for reasons other than those related to quality or fraud, to continue treatment with her provider, consistent with the carrier’s evidence of coverage, for a period up to and including the insured’s first postpartum visit.

Section 958 CMR 3.502. Disenrollment of Providers of Care to the Terminally Ill 

Continuity of Care Post-Contract

Carriers shall allow any insured who is terminally ill, and whose provider in connection with the treatment of the insured’s terminal illness is involuntarily disenrolled for reasons other than those related to quality or fraud, to continue treatment with the provider, consistent with the terms of the carrier’s evidence of coverage, until the insured’s death.

Section 958 CMR 3.503. Coverage for the Newly Insured 

Continuity of Care Post-Contract

(1) A carrier shall provide coverage for health services to a newly insured provided by a provider who is not a participating provider in the carrier’s network for up to 30 days from the effective date of coverage if:

(a) the insured’s employer only offers the insured a choice of carriers in which said provider is not a participating provider; and

(b) said provider is providing the insured with an ongoing course of treatment or is the insured’s primary care provider.

(2) With respect to an insured pregnant woman who is in her second or third trimester, coverage pursuant to 958 CMR 3.503(1) shall apply to services rendered through the insured’s first postpartum visit.

(3) With respect to an insured with a terminal illness, coverage pursuant to 958 CMR 3.503(1) shall apply to services rendered until the insured’s death.

Section 958 CMR 3.504. Carrier’s Coverage Conditions 

Continuity of Care Post-Contract

(1) A carrier may condition coverage of continued treatment by a provider under 958 CMR 3.500 through 3.502, upon the provider’s agreeing:

(a) to accept reimbursement from the carrier at the rates applicable prior to the notice of disenrollment as payment in full;

(b) to not impose cost sharing with respect to the insured in an amount that would exceed the cost sharing that could have been imposed if the provider had not been disenrolled;

(c) to adhere to the quality assurance standards of the carrier and to provide the carrier with necessary medical information related to the care provided; and,

(d) to adhere to such carrier’s policies and procedures, including procedures regarding referrals, obtaining prior authorization and providing treatment pursuant to a treatment plan, if any, approved by the carrier.

(2) A carrier may condition coverage of treatment by a provider under 958 CMR 3.503 upon the provider’s agreeing:

(a) to accept reimbursement from the carrier at the rates applicable to participating providers as payment in full;

(b) to not impose cost sharing with respect to the insured in an amount that would exceed the cost sharing that could have been imposed if the provider participated in the carrier’s network;

(c) to adhere to the quality assurance standards of the carrier and to provide the carrier with necessary medical information related to the care provided; and

(d) to adhere to the carrier’s policies and procedures, including procedures regarding referrals, obtaining prior authorization and providing treatment pursuant to a treatment plan, if any, approved by the carrier.

(3) Nothing in 958 CMR 3.500 through 3.502 or 3.504 shall be construed to require the coverage of benefits that would not have been covered if the provider involved had remained a participating provider. Nothing in 958 CMR 3.503 shall be construed to require coverage of benefits that would not have been covered if the provider involved was a participating provider.

Section 958 CMR 3.508. Denial of Provider Application

Carriers shall provide health care providers who are applying to be participating providers and who are denied such status with a written reason or reasons for the denial of such application.

Section 958 CMR 3.509: Provider Termination Without Cause Provisions

Termination/Termination-Due Process

(1) Contracts between carriers and health care providers shall state that neither the carrier nor the provider has the right to terminate the contract without cause.

(2) Carriers shall provide a written statement to a provider of the reason or reasons for such provider’s involuntary disenrollment.

See https://www.mass.gov/regulations/958-CMR-300-health-insurance-consumer-protection